SAT Question ebf8d2b7: Linear Equations In Two Variables answer and explanation with Desmos solution

Choice B is correct. It's given that it takes the machine $10$ minutes to make a large box. It's also given that $x$ represents the possible number of large boxes the machine can make each day. Multiplying $10$ by $x$ gives $10x$, which represents the amount of time spent making large boxes. It's given that it takes the machine $5$ minutes to make a small box. It's also given that $y$ represents the possible number of small boxes the machine can make each day. Multiplying $5$ by $y$ gives $5y$, which represents the amount of time spent making small boxes. Combining the amount of time spent making $x$ large boxes and $y$ small boxes yields $10x+5y$. It's given that the machine makes boxes for a total of $700$ minutes each day. Therefore $10x+5y=700$ represents the possible number of large boxes, $x$, and small boxes, $y$, the machine can make each day.